/Engine/Plugins/Experimental/Mutable/Source/MutableRuntime/Public/MuR/Image.h
Generate the mipmaps for images. if bGenerateOnlyTail is true, generates the mips missing fromBaseto LevelCount and sets them in Dest (the full chain is spit in two images). Otherwise generate the mips missing fromBaseup to LevelCount and append them in Dest to the already generatedBase's mips.
void ImageMipmap ( int32 CompressionQuality, [Image](API\Plugins\MutableRuntime\MuR\Image) * Dest, const [Image](API\Plugins\MutableRuntime\MuR\Image) * Base, int32 LevelCount, const [FMipmapGenerationSettings](API\Plugins\MutableRuntime\MuR\FMipmapGenerationSettings) &, bool bGenerateOnlyTail )